It is commonplace to provide an electrical connector on a vehicle for accepting a corresponding connector that is cable-connected to electrical components of a towed apparatus, e.g. a trailer, boat, etc. Because of the multiplicity of components in vehicles for such things as running lights, brake lights, and signal lights, as well as electric brakes and other auxiliary equipment, the vehicle connector may provide seven or more contact terminals, e.g. arrayed in a circular pattern about a central terminal. The towed apparatus, however, may not require connection to each contact terminal, and thus may include a connector having fewer contact terminals than the vehicle connector.
In such cases, adaptors have been developed for making appropriate electrical connections from a vehicle to a towed apparatus. For example, 7-way (on vehicle) to 4-way (on towed apparatus) adaptors are well known. Alternatively, vehicles have been provided with multiple connector types to eliminate the need for an adaptor. In one example, a vehicle may be provided with both 7-way and 4-way connectors, each having their own wiring harness and connections to the vehicle electrical system. When operating a towing vehicle for towing a trailer, problems can arise that may cause hazardous or unsafe driving conditions. For example, a light on a trailer may burn out or become disconnected, which may cause a driving hazard at night or in foggy conditions. In another situation, the trailer may include electrically assisted brakes, which may fail or become disconnected, resulting in increased stopping distance that may pose a driving hazard. Many of these driving hazards arise without notification to the driver. When the driver does not know that a hazardous condition exists, the driver cannot adjust driving techniques or immediately stop to fix of the failed component.